U.S. patent number 4,587,189 [Application Number 06/737,605] was granted by the patent office on 1986-05-06 for photoconductive imaging members with perylene pigment compositions.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Ah-Mee Hor, Rafik O. Loutfy.
United States Patent |
4,587,189 |
Hor , et al. |
May 6, 1986 |
Photoconductive imaging members with perylene pigment
compositions
Abstract
Disclosed is an improved layered photoresponsive imaging member
comprised of a supporting substrate; a vacuum evaporated
photogenerator layer comprised of a perylene pigment selected from
the group consisting of a mixture of
bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, and
bisbenzimidazo(2,1-a:2',1'-a)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-10,21-dione, and
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide); and an aryl
amine hole transport layer comprised of molecules of the following
formula: ##STR1## dispersed in a resinous binder and wherein X is
selected from the group consisting of halogen and alkyl.
Inventors: |
Hor; Ah-Mee (Mississauga,
CA), Loutfy; Rafik O. (Willowdale, CA) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
24964542 |
Appl.
No.: |
06/737,605 |
Filed: |
May 24, 1985 |
Current U.S.
Class: |
430/58.8; 398/4;
430/78 |
Current CPC
Class: |
G03G
5/047 (20130101); G03G 5/0659 (20130101); G03G
5/0657 (20130101); G03G 5/0614 (20130101) |
Current International
Class: |
G03G
5/047 (20060101); G03G 5/06 (20060101); G03G
5/043 (20060101); G03G 005/14 () |
Field of
Search: |
;430/59,78 |
Primary Examiner: Welsh; John D.
Attorney, Agent or Firm: Palazzo; E. O.
Claims
What is claimed is:
1. An improved layered photoresponsive imaging member comprised of
a supporting substrate; a vacuum evaporated photogenerator layer
comprised of a perylene pigment selected from the group consisting
of a mixture of
bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, and
bisbenzimidazo(2,1-a:2',1'-a)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-10,21-dione; and
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide); and an aryl
amine hole transport layer comprised of molecules of the following
formula: ##STR8## dispersed in a resinous binder and wherein X is
selected from the group consisting of halogen and alkyl.
2. An imaging member in accordance with claim 1 wherein the
supporting substrate is comprised of a conductive metallic
substance, or an insulating polymeric composition overcoated with
an electrically conductive layer.
3. An imaging member in accordance with claim 1 wherein the
supporting substrate is aluminum.
4. An imaging member in accordance with claim 1 wherein the
supporting substrate is overcoated with a polymeric adhesive
layer.
5. An imaging member in accordance with claim 4 wherein the
adhesive layer is a polyester resin.
6. An imaging member in accordance with claim 1 wherein X is
selected from (ortho)CH.sub.3, (meta)CH.sub.3, (para)CH.sub.3,
(ortho)Cl, (meta)Cl, and (para)Cl.
7. An imaging member in accordance with claim 1 wherein the aryl
amine is
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine.
8. An imaging member in accordance with claim 1 wherein the
resinous binder is a polycarbonate or polyvinylcarbazole.
9. An imaging member in accordance with claim 1 wherein the
perylene pigments are dispersed in a resinous binder in an amount
of from about 5 percent to about 95 percent by volume, and the aryl
amine hole transport molecules are dispersed in a resinous binder
in an amount of from about 10 to about 75 percent of weight.
10. An imaging member in accordance with claim 9 wherein the
resinous binder for the perylene pigments is a polyester,
polyvinylcarbazole, polyvinylbutyral, a polycarbonate, or a phenoxy
resin; and the resinous binder for the aryl amine hole transport
material a polycarbonate, a polyester, or a vinyl polymer.
11. An imaging member in accordance with claim 1 wherein the aryl
amine hole transport layer is situated between the supporting
substrate and the vacuum deposited photogenerating layer.
12. An imaging member in accordance with claim 11 comprised of a
supporting substrate; a photogenerator layer comprised of a
perylene pigment selected from the group consisting of a mixture of
bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, and
bisbenzimidazo(2,1-a:2',1'-a)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-10,21-dione, and
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide); and an aryl
amine hole transport layer.
13. An imaging member in accordance with claim 11 wherein the
supporting substrate is comprised of a conductive metallic
substance, or an insulating polymeric composition overcoated with
an electrically conductive layer.
14. An imaging member in accordance with claim 11 wherein the
supporting substrate is aluminum.
15. An imaging member in accordance with claim 11 wherein the
supporting conductive substrate is overcoated with a thin polymeric
adhesive layer.
16. An imaging member in accordance with claim 11 wherein the aryl
amine charge transporting layer comprises molecules of the formula:
##STR9## dispersed in a resinous binder and wherein X is selected
from the group consisting of halogen and alkyl.
17. An imaging member in accordance with claim 16 wherein X is
selected from (ortho)CH.sub.3, (meta)CH.sub.3, (para)CH.sub.3,
(ortho)Cl, (meta)Cl, and (para)Cl.
18. An imaging member in accordance with claim 16 wherein the aryl
amine is
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine.
19. An imaging member in accordance with claim 16 wherein the
resinous binder is a polycarbonate or polyvinylcarbazole.
20. An imaging member in accordance with claim 16 wherein the
perylene pigments are dispersed in a resinous binder in an amount
of from about 5 percent to about 95 percent by volume, and the aryl
amine hole transport molecules are dispersed in a resinous binder
in an amount of from about 10 to about 75 percent by weight.
21. A method of imaging which comprises forming an electrostatic
latent image on the imaging member of claim 1, causing development
thereof with toner particles; subsequently transferring the
developed image to a suitable substrate; and permanently affixing
the image thereto.
22. A method of imaging which comprises forming an electrostatic
latent image on the imaging member of claim 11, causing development
thereof with toner particles; subsequently transferring the
developed image to a suitable substrate; and permanently affixing
the image thereto.
23. A method of imaging which comprises forming an electrostatic
latent image on the imaging member of claim 12, causing development
thereof with toner particles; subsequently transferring the
developed image to a suitable substrate; and permanently affixing
the image thereto.
24. A method of imaging which comprises forming an electrostatic
latent image on the imaging member of claim 16 causing development
thereof with toner particles; subsequently transferring the
developed image to a suitable substrate; and permanently affixing
the image thereto.
Description
BACKGROUND OF THE INVENTION
This invention is generally directed to photoresponsive imaging
members, and more specifically the present invention is directed to
layered photoresponsive members having incorporated therein certain
perylene pigment compositions. Thus, in one embodiment the present
invention envisions the use of specific pigment compositions as
organic photogenerator materials in photoresponsive imaging members
containing therein arylamine hole transport molecules. The
aforementioned photoresponsive imaging members can be negatively
charged when the perylene photogenerating layer is situated between
the hole transport layer and the substrate; or positively charged
when the hole transport layer is situated between the
photogenerating layer and the supporting substrate. Additionally,
the photoresponsive imaging members with the perylene pigment
compositions as photogenerator substances, and wherein the member
further includes therein an aryl amine hole transport layer are
useful in electrophotographic imaging processes, especially
xerographic processes wherein negatively charged or positively
charged images are rendered visible with developer compositions of
the appropriate charge.
Layered photoresponsive imaging members are generally known,
reference for example U.S. Pat. No. 4,265,900, the disclosure of
which is totally incorporated herein by reference, wherein there is
described an imaging member comprised of a photogenerating layer,
and an aryl amine hole transport layer. Examples of substances
useful in the photogenerating layer of this patent include trigonal
selenium, metal phthalocyanines, and metal free phthalocyanines.
Additionally, there is described in U.S. Pat. No. 3,121,006 a
composite xerographic photoconductive member comprised of finely
divided particles of a photoconductive inorganic compound dispersed
in an electrically insulating organic resin binder. The binder
materials disclosed in the '006 patent comprise a material which is
incapable of transporting for any significant distance injected
charge carriers generated by the photoconductive particles.
Accordingly, as a result the photoconductive particles must be in a
substantially contiguous particle-to-particle contact throughout
the layer for the purpose of permitting charge dissipation required
for the cyclic operation. With a uniform dispersion of
photoconductive particles a relatively high volume concentration of
photoconductor material, about 50 percent by volume, is usually
necessary to obtain sufficient photoconductor particle-to-particle
contact for rapid discharge. This high photoconductive loading can
result in destroying the physical continuity of the resinous
binder, thus significantly reducing the mechanical properties
thereof. Illustrative examples of specific binder materials
disclosed in the '006 patent include polycarbonate resins,
polyester resins, polyamide resins, and the like.
Many other patents are in existence describing photoresponsive
devices including layered devices containing generating substances,
such as U.S. Pat. No. 3,041,167, which discloses an overcoated
imaging member with a conductive substrate, a photoconductive
layer, and an overcoating layer of an electrically insulating
polymeric material. This member is utilized in an
electrophotographic copying method by, for example, initially
charging the member with an electrostatic charge of a first
polarity, and imagewise exposing to form an electrostatic latent
image which can be subsequently developed to form a visible image.
Prior to each succeeding imaging cycle, the imaging member can be
charged with an electrostatic charge of a second polarity, which is
opposite in polarity to the first polarity. Sufficient additional
charges of the second polarity are applied so as to create across
the member a net electrical field of the second polarity.
Simultaneously, mobile charges of the first polarity are created in
the photoconductive layer such as by applying an electrical
potential to the conductive substrate. The imaging potential which
is developed to form the visible image is present across the
photoconductive layer and the overcoating layer.
Photoresponsive imaging members with squaraine photogenerating
pigments are also known, reference U.S. Pat. No. 4,415,639. In this
patent there is illustrated an improved photoresponsive imaging
member with a substrate, a hole blocking layer, an optional
adhesive interface layer, an organic photogenerating layer, a
photoconductive composition capable of enhancing or reducing the
intrinsic properties of the photogenerating layer, and a hole
transport layer. As photoconductive compositions for the
aforementioned member there can be selected various squaraine
pigments, including hydroxy squaraine compositions. Moreover, there
is disclosed in U.S. Pat. No. 3,824,099 certain photosensitive
hydroxy squaraine compositions. According to the disclosure of this
patent, the squaraine compositions are photosensitive in normal
electrostatographic imaging processes.
The use of selected perylene pigments as photoconductive substances
is also known. There is thus described in Hoechst European Patent
Publication Nos. 0040402, DE3019326, filed May 21, 1980, the use of
N,N'-disubstituted perylene-3,4,9,10-tetracarboxyldiimide pigments
as photoconductive substances. Specifically, there is disclosed in
this publication evaporated
N,N'-bis(3-methoxypropyl)perylene-3,4,9,10-tetracarboxyldiimide
dual layered negatively charged photoreceptors with improved
spectral response in the wavelength region of 400 to 700
nanometers. A similar disclosure is revealed in Ernst Gunther
Schlosser, Journal of Applied Photographic Engineering, Vol. 4, No.
3, page 118 (1978). There is also disclosed in U.S. Pat. No.
3,871,882 photoconductive substances comprised of specific
perylene-3,4,9,10-tetracarboxylic acid derivative dyestuffs. In
accordance with the teachings of this patent the photoconductive
layer is preferably formed by vapor depositing the dyestuff in a
vacuum. Also, there is specifically disclosed in this patent dual
layer photoreceptors with perylene-3,4,9,10-tetracarboxylic acid
diimide derivatives, which have spectral response in the wavelength
region of from 400 to 600 nanometers.
Moreover, there is disclosed in U.S. Pat. No. 4,419,427
electrographic recording mediums with a photosemiconductive double
layer comprised of a first layer containing charge carrier perylene
diimide producing dyes, and a second layer with one or more
compounds which are charge transporting materials when exposed to
light, reference the disclosure in column 2, beginning at line 20.
Also of interest with respect to this patent is the background
information included in columns 1 and 2, wherein perylene dyes of
the formula illustrated are presented.
Furthermore, there is presented in copending application U.S. Ser.
No. 587,483, now U.S. Pat. No. 4,514,482 entitled Photoconductive
Devices Containing Perylene Dye Compositions, the disclosure of
which is totally incorporated herein by reference, an ambipolar
imaging member comprised of a supporting substrate, a
photoconductive layer comprised of specific perylene dyes different
than the perylene pigments of the present invention, which dyes are
dispersed in a polymeric resinous binder composition; and as a top
layer a specific aryl amine hole transporting substance dispersed
in an inactive resinous binder. Examples of perylene dyes selected
for the photoconductive layer of the copending application include
N,N'-di(2,4,6-trimethylphenyl)perylene
3,4,9,10-tetracarboxyldiimide,
N,N'-di(2,4,6-trimethoxyphenyl)perylene
3,4,9,10-tetracarboxyldiimide, and
N,N'-di(2,6-dimethylphenyl)perylene
3,4,9,10-tetracarboxyldiimide.
Additionally, there is disclosed in U.S. Pat. No. 4,429,029
electrophotographic recording members with perylene charge carrier
producing dyes and a charge carrier transporting layer. The dyes
selected, which are illustrated in column 2, beginning at line 55,
are substantially similar to the photogenerating dyes of the
present invention. The aryl amine hole transporting compounds
selected for members of the present invention are, however, not
described in the U.S. Pat. No. 4,429,029 patent; and further with
the photoresponsive imaging members of the present invention the
photogenerating perylene layers are prepared by vacuum deposition
enabling superior image quality in comparison to the binder or
binderless dispersed layers obtained by the spray coating or
solution casting techniques as illustrated in the U.S. Pat. No.
4,429,029 patent. Vacuum deposition enables, for example, layers of
uniform thickness and substantial smoothness, as contrasted to
layers of ununiform thickness and surface roughness with binder or
binderless dispersed layers prepared by spray coating processes;
very thin layers of 0.1 microns or less are permitted whereas with
binder or binderless dispersed layers, thicknesses are generally
about 0.5 microns or more; and continuous layers with no large
voids or holes result, while dispersed layers usually contain holes
or voids thereby adversely affecting image resolution.
Furthermore, with the imaging members of the present invention
comprised of vacuum deposited perylenes, and aryl amine holes
transporting compounds superior xerographic performance occurs as
low dark decay characteristics result and higher photosensitivity
is generated, particularly in comparison to several prior art
imaging members prepared by solution coating or spray coating,
reference for example, U.S. Pat. No. 4,429,029 mentioned
hereinbefore.
While the above-described photoresponsive imaging members are
suitable for their intended purposes, there continues to be a need
for improved members, particularly layered members, having
incorporated therein specific perylene pigment compositions and
aryl amine hole transport compounds. Additionally, there continues
to be a need for layered imaging members comprised of specific aryl
amine charge transport compositions; and as photogenerating
materials perylene pigments with acceptable visible sensitivity,
low dark decay characteristics, high charge acceptance values, and
wherein these members can be used for a number of imaging cycles in
a xerographic imaging or printing apparatus. Furthermore, there
continues to be a need for photoresponsive imaging members which
can be positively or negatively charged thus permitting the
development of images, including color images, with positively or
negatively charged toner compositions. Moreover, there continues to
be an important need for disposable imaging members with nontoxic
organic pigments. Also, there is a need for disposable imaging
members useful in xerographic imaging processes, and xerographic
printing systems wherein, for example, light emitting diodes (LED),
helium cadmium, or helium neon lasers are selected; and wherein
these members are particularly sensitive to the visible region of
the spectrum, that is, from about 400 to about 800 nanometers.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide improved
photoresponsive imaging members which are substantially inert to
the users thereof.
It is yet another object of the present invention to provide
disposable layered photoresponsive imaging members.
A further specific object of the present invention resides in the
provision of an improved photoresponsive imaging member with an
aryl amine hole transport layer, and a photogenerator layer
comprised of specific perylene pigment compositions.
In yet another specific object of the present invention there is
provided negatively charged layered photoresponsive imaging members
vacuum evaporated perylene pigment compositions optionally
dispersed in a resinous binder, and thereon a hole transport layer
comprised of aryl amine molecules.
There is provided in another object of the present invention
positively charged layered photoresponsive imaging members with a
top vacuum evaporated perylene pigment composition optionally
dispersed in a resinous binder, and thereunder a hole transport
layer comprised of aryl amine molecules.
It is still another object of the present invention to provide
improved imaging members sensitive to light in the visible region
of the spectrum, that is, from about 400 to about 800
nanometers.
It is yet another object of the present invention to provide
imaging and printing methods with the improved photoresponsive
imaging members illustrated herein.
These and other objects of the present invention are accomplished
by the provision of photoresponsive imaging members having
incorporated therein vacuum evaporated photogenerating layers
comprised of known perylene pigment compositions selected from the
group consisting of ##STR2## wherein X is o-phenylene,
pyridimediyl, pyrimidinediyl, phenanthrenediyl, naphthalenediyl,
and the corresponding methyl, nitro, chloro, and methoxy
substituted derivatives; and ##STR3## wherein A is hydrogen, lower
alkyl of from 1 to about 4 carbon atoms, aryl, substituted aryl,
arylalkyl, alkoxyalkyl, carboxylate, a heterocyclic group,
alkoxyaryl; specific examples of which include methyl, ethyl,
phenyl, methoxy, ethoxy, propoxy, pyrroles, furan, imidazole,
esters, and quinolines.
Illustrative examples of perylene pigments useful for incorporation
into the imaging members of the present invention include those of
the following formulas: ##STR4## With further reference to the
perylenes of formula III, the cis isomer can be chemically
designated as
bisbenzimidazo(2,1-a-1',1'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, while the trans isomer has the chemical designation
bisbenzimidazo(2,1-a-1',1'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-10,21-dione.
The known perylene compositions illustrated herein are generally
prepared by the condensation reaction of perylene 3,4,9,10
tetracarboxylic acid or the corresponding anhydrides with an
appropriate amine in quinoline, in the presence of a catalyst, and
with heating at elevated temperatures, about 180.degree. C. to
about 230.degree. C., the details of which are described in German
Patent Publications Nos. 2,451,780; 2,451,781; 2,451,782;
2,451,783; 2,451,784; 3,016,765; French Patent No. 7723888; and
British Patent Nos. 857,130; 901,694; and 1,095,196, the disclosure
of each of the aforementioned publications and patents being
totally incorporated herein by reference.
The following equation details the acid catalyzed condensation in
acetic acid of 3,4,9,10-perylene tetracarboxylic dianhydride with
the o-phenylene diamine enabling the cis-trans mixture of Formula
III. ##STR5##
Similarly, the perylene of Formula IV can be prepared by reacting
perylene-3,4,9,10-tetracarboxylic dianhydride with aniline in
accordance with the following equation: ##STR6##
In one specific process embodiment, the perylene pigments of the
present invention can be prepared by the condensation reaction of
perylene-3,4,9,10-tetracarboxylic acid or its corresponding
anhydrides with an amine in a molar ratio of from about 1:2 to
about 1:10, and preferably in a ratio of from about 1:2 to about
1:3. This reaction is generally accomplished at a temperature of
from about 180.degree. C. to about 230.degree. C., and preferably
at a temperature of about 210.degree. C. with stirring and in the
presence of a catalyst. Subsequently, the desired product is
isolated from the reaction mixture by known techniques such as
filtration. Examples of reactants include
perylene-3,4,9,10-tetracarboxylic acid, and
perylene-3,4,9,10-tetracarboxylic acid dianhydride. Illustrative
amine reactants include o-phenylene diamine 2,3-diaminonaphthalene;
2,3-diamino pyridine; 3,4-diamino pyridine; 5,6-diamino pyrimidene;
9,10-diamino phenanthrene; 1,8-diamino naphthalene; aniline; and
substituted anilines.
Catalysts that can be used include known effective materials such
as anhydrous zinc chloride, anhydrous zinc acetate, zinc oxide,
acetic acid, hydrochloric acid, and the like.
Numerous different layered photoresponsive imaging members with the
perylene pigments illustrated herein can be fabricated. In one
embodiment, thus the layered photoresponsive imaging members are
comprised of a supporting substrate, an aryl amine hole transport
layer, and situated therebetween a vacuum evaporated photogenerator
layer comprised of the perylene pigments illustrated hereinbefore.
Another embodiment of the present invention is directed to
positively charged layered photoresponsive imaging members
comprised of a supporting substrate, an aryl amine hole transport
layer, and as a top overcoating a vacuum evaporated photogenerator
layer comprised of the perylene pigments illustrated hereinbefore.
Moreover, there is provided in accordance with the present
invention an improved negatively charged photoresponsive imaging
member comprised of a supporting substrate, a thin adhesive layer,
a photogenerator vacuum evaporated layer comprised of the perylene
pigments illustrated herein optionally dispersed in a polymeric
resinous binder, and as a top layer aryl amine hole transporting
molecules dispersed in a polymeric resinous binder.
The improved photoresponsive imaging members of the present
invention can be prepared by a number of methods, the process
parameters and the order of coating of the layers being dependent
on the member desired. Thus, for example, these imaging members are
prepared by vacuum deposition of the photogenerator layer on a
supporting substrate with an adhesive layer thereon, and
subsequently depositing by solution coating the hole transport
layer. The imaging members suitable for positive charging can be
prepared by reversing the order of deposition of photogenerator and
hole transport layers.
Imaging members having incorporated therein the perylene pigments
of the present invention are useful in various electrostatographic
imaging systems, particularly those conventionally known as
xerographic processes. Specifically, the imaging members of the
present invention are useful in xerographic imaging processes
wherein the perylene pigments absorb light of a wavelength of from
about 400 nanometers to about 800 nanometers. In these processes,
electrostatic latent images are initially formed on the imaging
member followed by development, and thereafter transferring the
image to a suitable substrate.
Moreover, the imaging members of the present invention can be
selected for electronic printing processes with gallium arsenide
light emitting diodes (LED) arrays which typically function at
wavelengths of 660 nanometers.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention and further
features thereof, reference is made to the following detailed
description of various preferred embodiments wherein:
FIG. 1 is a partially schematic cross-sectional view of a
negatively charged photoresponsive imaging member of the present
invention;
FIG. 2 is a partially schematic cross-sectional view of a
positively charged photoresponsive imaging member of the present
invention;
FIG. 3 is a line graph illustrating the spectral response of
specific perylene pigments of the present invention;
FIGS. 4 and 5 are photosensitivity curves for specific perylene
pigments of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Illustrated in FIG. 1 is a negatively charged photoresponsive
imaging member of the present invention comprised of a substrate 1,
an adhesive layer 2, a vacuum evaporated photogenerator layer 3,
comprised of a mixture of the cis and trans isomers of
bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, and
bis-benzimidazo(2,1-a:2',1'-a')anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoli
ne-10,21-dione; and a charge transport layer 5, comprised of
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine,
dispersed in a polycarbonate resinous binder 7.
Illustrated in FIG. 2 is a positively charged photoresponsive
imaging member of the present invention comprised of a substrate
10, a charge transport layer 12, comprised of
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine,
dispersed in a polycarbonate resinous binder 14, and a
photogenerator layer 16, applied by vacuum evaporation, comprised
of a mixture of the cis and trans isomers of
bisbenzimidazo(2,1-a-1',2'-b)anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoline
-6,11-dione, and
bis-benzimidazo(2,1-a:2',1'-a')anthra(2,1,9-def:6,5,10-d'e'f')diisoquinoli
ne-10,21-dione, optionally dispersed in an inactive resinous binder
18.
Similarly, there is included within the present invention
photoresponsive imaging members as described herein with reference
to FIG. 1 with the exception that there can be selected as the
photogenerator the perylene pigments
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide), (Formula IV).
Also envisioned are positively charged imaging members as described
with reference to FIG. 2, with the exception that there is selected
as the photogenerator perylene pigment
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide), (Formula
IV).
Illustrated in FIG. 3 is a plot of the E.sub.1/2 value versus
wavelength in nanometers for photoresponsive imaging members
prepared in accordance with Example III. Specifically, curve 1
represents the light sensitivity of the imaging member of Example
III with a benzimidazole perylene of Formula III. This sensitivity
is substantially greater than identical imaging members prepared by
the procedure of Example III, with the exception that for curve 2
there was selected the prior art perylene
N,N'-di(methoxypropyl)-3,4,9,10-perylenebis(dicarboxyamide); and
for curve 3 the prior art perylene
N,N'-dimethyl-3,4,9,10-perylenebis(dicarboxyamide) was selected
instead of in each instance the benzimidazole of Formula III.
FIG. 4 illustrates the photosensitivity curve for the imaging
member of FIG. 1 the photogenerating layer indicated and wherein
the percentage of discharge from an initial surface potential of
-830 volts is plotted against the light exposure energies
recited.
FIG. 5 illustrates a photosensitivity curve for the imaging member
of FIG. 1 wherein the photogenerator layer is an evaporated film of
the N,N'-diphenyl perylene (Formula IV) indicated.
Substrate layers selected for the imaging members of the present
invention can be opaque or substantially transparent, and may
comprise any suitable material having the requisite mechanical
properties. Thus, the substrate may comprise a layer of insulating
material including inorganic or organic polymeric materials, such
as Mylar a commercially available polymer; a layer of an organic or
inorganic material having a semiconductive surface layer such as
indium tin oxide, or aluminum arranged thereon, or a conductive
material inclusive of aluminum, chromium, nickel, brass or the
like. The substrate may be flexible or rigid and many have a number
of many different configurations, such as, for example a plate, a
cylindrical drum, a scroll, an endless flexible belt and the like.
Preferably, the substrate is in the form of a seamless flexible
belt. In some situations, it may be desirable to coat on the back
of the substrate, particularly when the substrate is a flexible
organic polymeric material, an anti-curl layer, such as for example
polycarbonate materials commercially available as Makrolon.
The thickness of the substrate layer depends on many factors,
including economical considerations, thus this layer may be of
substantial thickness, for example, over 2,500 microns; or of
minimum thickness providing there are no adverse effects on the
system. In one preferred embodiment, the thickness of this layer
ranges from about 75 microns to about 250 microns.
With further regard to the imaging members of the present
invention, the photogenerator layer is preferably comprised of 100
percent of the perylene pigments disclosed herein. However,
providing the objectives of the present invention are achieved,
these perylene pigments can be dispersed in resinous binders.
Generally, the thickness of the perylene photogenerator layer
depends on a number of factors including the thicknesses of the
other layers, and the percent mixture of photogenerator material
contained in this layer. Accordingly, this layer can be of a
thickness of from about 0.05 micron to about 10 microns when the
photogenerator perylene composition is present in an amount of from
about 5 percent to about 100 percent by volume. Preferably this
layer is of a thickness of from about 0.25 micron to about 1
micron, when the photogenerator perylene composition is present in
this layer in an amount of 30 percent by volume. In one very
specific preferred embodiment, the vacuum deposited photogenerating
layers are of a thickness of from about 0.07 micron to about 0.5
micron. The maximum thickness of this layer is dependent primarily
upon factors such as photosensitivity, electrical properties and
mechanical considerations.
Illustrative examples of polymeric binder resinous materials that
can be selected for the photogenerator pigment include those
polymers as disclosed in U.S. Pat. No. 3,121,006, the disclosure of
which is totally incorporated herein by reference, polyesters,
polyvinyl butyral, Formvar.RTM., polycarbonate resins, polyvinyl
carbazole, epoxy resins, phenoxy resins, especially the
commercially available poly(hydroxyether) resins, and the like.
As adhesives there can be selected various known substances
inclusive of polyesters such as those commercially available from
E. I. DuPont as 49,000 polyesters. This layer is of a thickness of
from about 0.05 micron to 1 micron.
Arylamines selected for the hole transporting layer which generally
is of a thickness of from about 5 microns to about 50 microns, and
preferably of a thickness of from about 10 microns to about 40
microns, include molecules of the following formula: ##STR7##
dispersed in a highly insulating and transparent organic resinous
binder wherein X is an alkyl group or a halogen, especially those
substituents selected from the group consisting of (ortho)CH.sub.3,
(para)CH.sub.3, (ortho)Cl, (meta)Cl, and (para)Cl.
Examples of specific arylamines are
N,N'-diphenyl-N,N'-bis(alkylphenyl)-[1,1-biphenyl]-4,4'-diamine
wherein alkyl is selected from the group consisting of methyl such
as 2-methyl, 3-methyl and 4-methyl, ethyl, propyl, butyl, hexyl,
and the like. With chloro substitution, the amine is
N,N'-diphenyl-N,N'-bis(halo phenyl)-[1,1'-biphenyl]-4,4'-diamine
wherein halo is 2-chloro, 3-chloro or 4-chloro.
Examples of the highly insulating and transparent resinous material
or inactive binder resinous material for the transport layers
include materials such as those described in U.S. Pat. No.
3,121,006, the disclosure of which is totally incorporated herein
by reference. Specific examples of organic resinous materials
include polycarbonates, acrylate polymers, vinyl polymers,
cellulose polymers, polyesters, polysiloxanes, polyamides,
polyurethanes and epoxies as well as block, random or alternating
copolymers thereof. Preferred electrically inactive binders are
comprised of polycarbonate resins having a molecular weight of from
about 20,000 to about 100,000 with a molecular weight of from about
50,000 to about 100,000 being particularly preferred. Generally,
the resinous binder contains from about 10 to about 75 percent by
weight of the active material corresponding to the foregoing
formula, and preferably from about 35 percent to about 50 percent
of this material.
Also, included within the scope of the present invention are
methods of imaging with the photoresponsive devices illustrated
herein. These methods generally involve the formation of an
electrostatic latent image on the imaging member, followed by
developing the image with a toner composition, subsequently
transferring the image to a suitable substrate, and permanently
affixing the image thereto. In those environments wherein the
device is to be used in a printing mode, the imaging method
involves the same steps with the exception that the exposure step
can be accomplished with a laser device or image bar.
The invention will now be described in detail with reference to
specific preferred embodiments thereof, it being understood that
these examples are intended to be illustrative only. The invention
is not intended to be limited to the materials, conditions, or
process parameters recited herein, it being noted that all parts
and percentages are by weight unless otherwise indicated.
EXAMPLE I
Synthesis of benzimidazole perylene (Formula III)
There was mixed in a three-liter flask 5.85 grams of
3,4,9,10-perylenetetracarboxylic dianhydride, 26.77 grams of
o-phenylene diamine and 7 milliliters of glacial acetic acid. The
mixture resulting was then heated with stirring for 8 hours at
210.degree. C., followed by cooling to room temperature. A solid
product was then obtained by filtering the mixture throught a
sintered glass funnel; followed by washing with 1,000 milliliters
of methanol. Thereafter, the solid was slurried with 500
milliliters of 1 percent sodium hydroxide solution. After
filtration, the solid was washed with 600 milliliters of water, and
then was dried in an oven at 80.degree. C. overnight yielding 7.62
grams, of the above product III.
EXAMPLE II
Synthesis of N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide)
(Formula IV)
The procedure of Example I was repeated with the exception that the
o-phenylene diamine reactant was replaced with 23.8 milliliters of
aniline, yielding 7.0 grams of the above product IV.
EXAMPLE III
A photoresponsive imaging member was prepared by providing an
aluminized Mylar substrate in a thickness of 75 microns, with a
DuPont 49,000 polyester adhesive layer thereon in a thickness of
0.05 microns, and depositing thereover with a Varian Model 3117
vacuum coater a photogenerating layer of the benzimidazole perylene
of Formula III at a final thickness of 0.1 microns. The
photogenerator pigment was heated in a tantalum boat to about
350.degree. C., and the vacuum coater evacuated to a pressure of
about 10.sup.-5 torr. Also, the substrate was mounted 16
centimeters from the boat, and the photogenerator layer was
deposited at a rate of about 4 Angstroms/sec.
Thereafter, the above photogenerating layer was overcoated with an
amine charge transport layer prepared as follows:
A transport layer with 65 percent by weight Merlon, a polycarbonate
resin, was mixed with 35 percent by weight
N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine,
to 7 percent by weight in methylene chloride in an amber bottle.
The resulting mixture was then coated in a dry thickness of 15
microns on top of the above photogenerating layer, using a multiple
clearance film applicator (10 mils wet gap thickness). The
resulting member was then dried in a forced air oven at 135.degree.
C. for 20 minutes.
The photosensitivity of this member was then determined by
electrostatically charging the surface thereof with a corona
discharge source until the surface potential, as measured by a
capacitively coupled probe attached to an electrometer, attained an
initial dark value V.sub.O of -800 volts. The front surface of the
charged member was then exposed to light from a filtered Xenon
lamp, XBO 75 watt source, allowing light in the wavelength range
400 to 800 nanometers to reach the member surface. The exposure
causing reduction of the surface potential to half its initial
value, E.sub.1/2, and the percent discharge of surface potential
due to various exposure energies was then determined. The
photosensitivity can be determined in terms of the exposure in
ergs/cm.sup.2 necessary to discharge the member from the initial
surface potential to half that value. The higher the
photosensitivity, the smaller the exposure energy required to
discharge the layer to 50 percent of the surface potential. The
photosensitivity results are illustrated in FIG. 4 wherein the
percent discharge of surface potential is plotted against various
exposure energies. With white light, 400 to 800 nanometers
exposure, the E.sub.1/2 value was found to be 4.7 erg/cm.sup.2, and
the percent discharge at an exposure level of 10 erg/cm.sup.2 was
74.
EXAMPLE IV
A photoresponsive imaging member was prepared by repeating the
procedure of Example III with the exception that there was selected
as the photogenerating pigment
N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide) in the thickness
of 0.1 micron. Thereafter, the photosensitivity of the resulting
member was determined by repeating the procedure of Example III
with the results of this determination being illustrated in FIG. 5.
FIG. 5 is the percent discharge of surface potential plotted
against various exposure energies. Specifically with further
reference to FIG. 5, at a white light exposure of 400 to 700
nanometers, the E.sub.1/2 was found to be 12 ergs/cm.sup.2 ; and
the percent discharge at an exposure level of 10 ergs/cm.sup.2 was
41.
EXAMPLE V
A photoresponsive imaging member was prepared by repeating the
procedure of Example III with the exception that there was selected
as the photogenerating layer the benzimidazole perylene of Formula
III in thickness of 0.1 and 0.25 microns respectively.
The photosensitivity of the resulting member was determined
according to the procedure of Example III, with the following
results:
______________________________________ Thickness of Photogenerating
E.sub.1/2, % Discharge Layer of Benzimidazole Perylene erg/cm.sup.2
at 10 erg/cm.sup.2 ______________________________________ 0.1
microns 4.7 74 0.25 microns 4.1 81
______________________________________
The 0.25 micron member is slightly more sensitive than the 0.1
micron member. Compared with the imaging member of Example IV
comprised of an N,N'-diphenyl-3,4,9,10-perylenebis(dicarboximide)
photogenerating layer, the 0.25 micron member is about three times
more sensitive, reference the E.sub.1/2 values.
The higher sensitivity of imaging members containing the
benzimidazole perylene photogenerator layer is attributed to the
wider light absorption range of the benzimidazole perylene as
compared to other perylenes.
Most perylenes only absorb light in the wavelength region ranging
from 400 to 600 nanometers with a maximum absorption occurring at
about 500 nanometers. However, the optical absorption spectrum of
the Formula III benzimidazole film vacuum deposited onto a glass
slide, evidences a broader absorption characteristic of from 400 to
800 nanometers with absorption peaks situated at 525 and 675
nanometers. The light absorption property beyond 600 nanometers
enables the benzimidazole perylene to capture more light,
especially from the white light generated in xerographic processes.
Also, the benzimidazole perylene imaging element can be used in
conjunction with a 630 nanometers He/Ne laser commonly used in
electronic printing machines. Similarly, the benzimidazole perylene
imaging element can be selected for use with GaAsP light emitting
diode (LED) arrays operating at a wavelength of 660 nanometers in
electronic printers.
EXAMPLE VI
The imaging member of FIG. 2 was prepared by repeating the
procedure of Example III, with the exception that the amine
transport layer was initially coated onto the aluminized Mylar
substrate, followed by the photogenerator layer of benzimidazole
perylene (Formula III), 0.07 microns. A second imaging member was
then prepared by repeating the aforementioned procedure with the
exception that the perylene layer had a thickness of 0.10
microns.
The photosensitivity of the two imaging members fabricated was then
evaluated by repeating the procedure of Example III with the
exception that the members were charged to a positive 800 volts,
followed by exposure to white light. The photosensitivity results
are summarized in the table.
______________________________________ Thickness of Photogenerating
E.sub.1/2, % Discharge Layer of Benzimidazole Perylene erg/cm.sup.2
at 10 erg/cm.sup.2 ______________________________________ 0.07
microns 27 21 0.10 microns 31 22
______________________________________
EXAMPLE VII
Benzimidazole perylene, 17 grams, and 0.40 grams of Goodyear's
PE200 polyester were mixed in a 30 cc glass bottle containing 70
grams of 1/8 inch stainless steel shots and 13.5 grams of methylene
chloride. The bottle was put on a roller mill and the mixture was
milled for 24 hours. Thereafter, the polyester dispersion solution,
30 percent by weight of the perylene pigment, was then coated onto
an aluminized Mylar substrate using a film applicator of 1 mil gap,
followed by drying at 135.degree. C. for 20 minutes. Subsequently,
the transport layer was coated onto the generator layer according
to the procedure described in Example I.
Similarly, a second binder layer was prepared as described before
except that polyvinylcarbazole (PVK) was used to replace the PE200
polyester.
The following table compares the photosensitivity results of
various imaging members, with the above binder generator layers, as
compared to the vacuum deposited generator layers of Example IV.
Equivalent amount of perylene are present in the three generator
layer being compared.
______________________________________ E.sub.1/2, % Discharge Type
of Photogenerator Layer erg/cm.sup.2 at 10 erg/cm.sup.2
______________________________________ PE200 Binder 8.0 60 PVK
Binder 8.7 55 0.1 micron vacuum deposited 4.7 74
______________________________________
The vacuum deposited benzimidazole perylene photogenerator layer
evidences higher photosensitivity, reference a lower E.sub.1/2
value and higher percent discharge at 10 erg/cm.sup.2 than the
binder layered imaging members.
Other modifications of the present invention may occur to those
skilled in the art based upon a reading of the present disclosure
and these modifications, including equivalents thereof, are
intended to be included within the scope of the present
invention.
* * * * *